The invention relates to a volume flow or pressure regulating device which is particularly suitable for use in controlling, in a closed loop manner, a flow of gas, especially in air ducts as they are used in air heating and air conditioning systems. Such regulating devices generally comprise a control flap rigidly secured to a shaft which in turn is rotatable by a control member such as a lever or the like.
For maintaining the air flow volume constant, or for maintaining the air pressure constant in a channel or duct it is necessary that the closed loop control transmits a certain torque moment to the flap shaft as a function of or in response to the flap angle. Prior art regulating devices of this type are not sufficiently responsive or sensitive to pressure differentials across the flap. Further, the permissible tolerance range as a proportion of the maximum volume flow leaves room for improvement as does the noise generated by such prior art flaps.